In one form of high-speed printing press, a conveyor system carries printed copy from the press to automatic stackers. In these conveyors there is fitted a hinged section which can be dropped to divert the copy (to a waste conveyor running underneath) by closing a switch on the operator's console. This hinged section, or dump gate, is dropped whenever unsatisfactory copy is being printed, such as during "make ready" or when a splice is made on the incoming reels of paper.
An object of this invention is to provide a control system capable of dropping the dump gate automatically when a splice (marred by glue) is leaving the press, enabling this splice to be made at the press running speed.
In accordance with this invention, there is provided a system for controlling a dump gate in a conveyor system, comprising means for detecting a marker carried by a marred product in a succession of products being conveyed and to start a counter, and means for opening the dump gate once a predetermined number of said products has been counted as passing a predetermined point along the conveyor, and for closing the dump gate again once a further predetermined number of products has been counted past.
In an embodiment of control system to be described below, a metal tab is fitted to a new reel of paper when preparing the splice: once the splice has been made, the metal tab is detected on the press delivery conveyor immediately upstream of the dump gate. The number of copies passing is then counted and at a preset count the gate is lowered, then at a further preset number it is raised again. Complete control is thus achieved over the number of copies which are rejected and the gate is lowered only when the splice appears and closed immediately after the splice, regardless of the press and conveyor speed.
This embodiment of our control system includes two electronics counters, which are forced to respective preset counts (the pre-dump and end-dump copy counts) when the tab is detected. The two counters are then decremented by the successive copies passing, until the pre-dump counter reaches zero (whereupon a solenoid for opening the gate is energised) and then later the end-dump counter reaches zero (whereupon the dump solenoid is de-energised to allow the gate to close again).